-LRB- CNN -RRB- -- Afghan insurgents who staged a daring , well-planned raid on Camp Bastion , the military base where Britain 's Prince Harry is deployed , were wearing U.S. Army uniforms , NATO said a day after the attack .

It 's extremely rare for Afghan insurgents to use U.S. uniforms in their attacks . The last time CNN can identify was more than two years ago , when NATO repelled attacks on two bases in Khost province in August 2010 .

No coalition troops were killed in that attack , NATO 's International Security Assistance Force said at the time .

At least two U.S. Marines were killed in the brazen strike late on Friday , and six jets were destroyed , ISAF said as it released more details about the raid .

Well-trained , well-rehearsed fighters carried out the sustained assault in Helmand province , ISAF said .

About 15 insurgents organized into three teams penetrated the base 's perimeter fence and did considerable damage , destroying six refueling stations and damaging six aircraft hangars .

The attackers toted automatic rifles , rocket-propelled grenade launchers and suicide vests .

They destroyed six AV-8B Harrier jets and damaged two others before the attack ended , the coalition said .

Fourteen of the fighters were killed and one was wounded and captured , ISAF said .

Eight coalition military personnel and one civilian contractor were also wounded .

It is too soon to say whether the attackers had `` inside knowledge , '' ISAF spokesman James Graybeal said .

ISAF would not say how the attackers got the uniforms , but CNN staff who have spent time in Afghanistan say they are for sale in markets there .

There has been at least one other case of Afghan insurgents wearing U.S. uniforms , in May 2010 .

And in Iraq five years ago , there was a dramatic and successful raid using the tactic .

Attackers wearing what appeared to be American uniforms were responsible for the kidnapping and killing of five U.S. soldiers in Karbala , Iraq , in 2007 .

Prince Harry is an Apache helicopter pilot based at Camp Bastion , but the British Ministry of Defence categorically rejected reports in Sunday 's British press that he was just a few hundred yards away from the gun battle .

Harry , a grandson of Queen Elizabeth II and third in line to the British throne , `` was in no way in any danger '' during the latest attack , ISAF spokesman Maj. Martin Crighton said earlier .

On Saturday , ISAF said the camp is secure and the strike would not `` impact '' air and ground operations .

Camp Leatherneck , the U.S. side of the base , was not affected by the attack , Maj. Adam N. Wojack , an ISAF spokesman , told CNN .

The joint base is located in a remote desert region of Helmand , the southern province in the Taliban heartland .

The Taliban said it carried out the strike , calling it a response to the anti-Islam film stoking anger among Muslims . Yet Crighton said there had no organized demonstrations outside its gates before the assault .

Afghanistan has seen only relatively small and peaceful demonstrations against the film during a week in which there were protests across predominantly Muslim-countries and other locations .

Separately , four American troops were killed by Afghan police on Sunday , an administration official said after NATO 's International Security Assistance Force reported the attack .

The latest attack on coalition troops by their supposed Afghan allies brings the number of people killed in so-called `` green on blue '' incidents to more than 50 this year .

The killing of the four Americans on Sunday is the latest in a series of incidents in which members of Afghan security forces have been suspected of turning their weapons on coalition or Afghan soldiers , known as green-on-blue attacks .

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Sunday 's killings came only a day after the British Ministry of Defence announced that two troops had been killed in Helmand province 's Nahr-e Saraj district .

In that attack , a man wearing an Afghan police uniform fatally shot two members of the 3rd Battalion at a checkpoint , according to Maj. Laurence Roche , a spokesman for Task Force Helmand , said in a statement released by the ministry .

The killing occurred the same day that another British soldier died in in a separate incident in Nahr-e Saraj , according to the ministry . He was killed when his vehicle struck a bomb .

CNN 's Chelsea J. Carter , Adam S. Levine , Kevin Flower , Jessica King and Greg Botelho contributed to this report .

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NEW : It appears to be the first time Afghan insurgents have worn U.S. uniforms in years

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Insurgents in U.S. Army uniforms attack the camp where Prince Harry is based

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The well-trained , well-armed attackers kill two Marines and destroy six jets

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Four NATO troops killed by Afghan police were American , an official says